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Design of Pixel Circuit of Micro LED Display with Double Gate Thin Film Transistors  

Kim, Taesoo (School of Electronics and Information Engineering, Korea Aerospace University)
Jeon, Jaehong (School of Electronics and Information Engineering, Korea Aerospace University)
Publication Information
Journal of the Semiconductor & Display Technology / v.21, no.1, 2022 , pp. 50-55 More about this Journal
Abstract
Due to the wavelength shift problem of micro LED caused by the change of current density, the active matrix driving pixel circuit that is used in OLED cannot be applied to micro LED displays. Therefore, we need a gray scale method based on modulation of duration time of light emission. In this study, we propose the PWM-controlled micro LED pixel circuit based on CMOS thin film transistors (TFTs). By adopting CMOS inverter structure, we can reduce the number of storage capacitors from the circuit and make the operating speed of the circuit faster. Most of all, our circuit is designed to make operating speed of PWM circuit faster by adopting feedback effect through double gate TFT structure. As a result, it takes about 4.7ns to turn on the LED and about 5.6ns to turn it off. This operating time is short enough to avoid the color distortion and help the precise control of the gray scale.
Keywords
Micro LED; Pulse width modulation; Double gate structure; CMOS inverter;
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